Franka, I've had a thought reading a few of your posts. What car is the unit installed in? Did you install an aftermarket wiring harness before installing the unit? Lots of cars (especially Volkswagen) require an extra wiring harness to convert them to the more standardized aftermarket wiring configuration. If you did not install an aftermarket loom, it's very possible the wiring configuration is wrong.
I have a very simple suggestion to test this theory. I would switch the accessory 12v and constant 12v, on the head unit wiring loom. The easiest way of doing this is by snipping both wires and installing bullet connectors on the two (now four) wires. Remember to put the male connectors on the non-live side. Alternatively, you can pop the wires out as the ISO plugs are designed to allow them to release, however I prefer bullets as they are just so much quicker and easier. Some aftermarket wiring looms actually come pre-fitted with bullet connectors so you can do just this (
[Please Register or Login to download file] ), so please don't be alarmed about fitting them, they're very common.
I find popping wires out of ISO plugs a nightmare, however if you don't want to cut the wires, you can pop them out by sticking a thin flat headed screwdriver through the plug side and levering them out.
To explain in more detail, these units will ONLY run when both are detected (so if one is cut, the unit will power down) however, the device has a permanent live which is powering the internal memory and controls the suspension mode on the WinCE. The accessory live as you put it, otherwise known as ignition live, merely powers the simple functions of the device e.g. ON/OFF, DVD Mechanism, Memory Card Readers, WinCE power itself etc, ie, when you turn your key to the first notch you will often hear the Mechanism spin-up. One way I can prove it, when wired up correctly, if the WinCE board crashes in a way that turning the ignition OFF won't fix, then you will have to cut the main power by removing the fuse from your fuse box. Pressing the hard reset button merely cuts the line between constant 12v and the unit, which will clear the internal memory, but will not reset the WinCE side of the device as it will continue to draw power from the accessory line which is still live.
Give it a try, post here how you get on